The present invention relates to a data input device which has an interface circuit to be connected to digital equipment and inputs data to the digital equipment. The present invention also relates to a data input method and an image output system using such a data input device.
A digital camera device photographs a subject and stores image data pertaining to the subject in a built-in recording medium as a data file. When the data file of the image data is fetched, terminal equipment, such as a personal computer, is connected to a digital camera device. The data file of the image data stored in the digital camera device is transferred to the terminal equipment (see, e.g., Japanese Patent Publication No. 2001-238156A). In this context, the digital camera device can be regarded as a data input device which has an interface circuit connected to another piece of digital equipment (i.e., terminal equipment) and inputs data to the equipment.
There has recently been developed a so-called direct print system, wherein a digital camera device is connected directly to a printer, and images captured by the digital camera device are printed without use of a personal computer or the like. The direct print system can be regarded as a kind of image output system, and direct print systems can be categorized into a system for transferring an image data file of a JPEG (Joint Picture Experts Group) format, and a system for generating a print control command, such as an ESC/P (Epson Standard Code for Printer), from image data through use of a digital camera device and transferring the print control command to a printer.
A USB (Universal Serial Bus) or the like is frequently used as an interface between such a digital camera device, the terminal equipment, and the printer. According to the USB standards, a first interface circuit of two pieces of mutually-connected equipment is taken as a device, and the other piece of equipment; that is, a second interface circuit, is taken as a host. Specifically, the USB standards are interface standards for imparting different roles to the interface circuits of the two pieces of mutually-connected equipment.
Recently, On-The-Go standards have been designated in connection with the USB standards. According to the On-The-Go standards, two functions; that is, an interface function of the host and that of a device, are implemented on one device. Either the interface function of the host or that of the device is used, as required.
As mentioned above, various pieces of digital equipment having interface circuits of identical interface standards are often connected to the digital camera device serving as a data input device. Therefore, by way of a physical cable, digital equipment can be connected to the digital camera device.
However, compatibility between vendors cannot be achieved by an application which is higher in level than the interface (e.g., the USB) interconnecting pieces of equipment, and, even within the range of compatible vendors, in some cases compatibility is not achieved, depending on the type of equipment. Although a data input device can be physically connected to another piece of digital equipment, the user cannot use the data input device and another digital equipment in conjunction with each other, thereby posing inconvenience to the user.
Currently, for instance, the above-described direct print system frequently uses a USB as an interface. However, there are many cases where a communication scheme, which is higher in level than the USB, and an application are frequently prepared to specifications that are unique to the vendor. Moreover, as a result of emergence of the On-The-Go standards of the USB, this situation is considered to become more noticeable.